HarrisH

iTrader: (1)

Ok I will try to explain this to the best of my ability. I have a '97 Auto. My orginal alternator was fluctuating the charge causing hesitations at stop lights or while driving, and fluctuating the charge between 14.5-15.1 volts. We (mechanic(s) and I) that it was most def. the alternator and that it was overcharging, and or fluctuating the charge in my car. So we get a new alternator (remanufactured one), and voila it's charging at a consistent 14.3 volts without any hesitations or fluctuation. Fast forward a few weeks later, I start noticing a very slight hesitation at stoplights. In other words with the original alternator the hesitation was very noticeable and annoying also scary because I thought my alternator would crap out any second. Let's say I'm sitting at a light my RPM should be at about 600-650 and the interior illuminated lights (all of the int. LEDS), should be solid, well with the orginal alternator the rpm would jump from 625-675 causing the illuminated int. LEDS to dim, then get bright, all VERY VERY rapidly. With the new alternator the same thing was happening just not as harshly. In other words you can barely see the int. illuminated lights get dim, and then bright, it was happening very very rapidly but it was a lot more subtle. So we (mechanic and I) decided the alternator was going bad again, so we replaced it with another one. Guess what, the "battery" light came on it was overcharging the car CONSISTENTLY at about 15V if not more than 15V. So I left the car overnight and put in the new alternator. Guess what same deal! It's fluctuating the charge but it's not as harsh as the original alternator. This is getting really really annoying, I don't know what it is or what to check anymore. Can 4 alternators be defective?

HarrisH

iTrader: (1)

The fluctuation can be best described as this. Imagine a car with an alternator or charging system that fluctuates the whole car's electrical system between 14.3-14.8 V consistently. But this does not happen all the time, sometimes only when I'm at idle, rarely ever when I'm driving. Guys I really need to figure this out .

njmaxseltd

iTrader: (19)

Harris, hate to burst your bubble, but it's your non constant idle speed thats causing the output of the alternator to fluctuate like that.

Your alternator is not the cause of your problem.
Stabalize the idle speed and your electrical system will become stable as well.

P.S. Were going to try to have your car ready tomorrow, Wednesday1/26..
The paint looks awsome, but we've got a lot of assembly and cleaning still to do.

P.S.S. Find another mechanic to work on your car or stop trying to be your own mechanic.

killcrap

iTrader: (3)

1 answer, replace your battery. or check your ignition, i suggest you do both.

HarrisH

iTrader: (1)

The battery is a brand new optima, what should I check in the ignition? Tom yeah please have it back by tomorrow it has been a while, I'm glad it looks good . My mechanic is very knowledgeable and always helps me out, we did presume it was the alternator because every alternator showed different issues. Consistently overcharging at 15.3V may not be my idle speed, because when we put in another alternator it was charging noramlly, just the very minor fluctuations. Can you guide me as to how to check/adjust the constant idle speed? Would I get a CEL if it was bad?

HarrisH

iTrader: (1)

BTW, if you are talking about the black screw right by the TPS connectors I adjusted that already, matter of fact I adjusted it several times.

njmaxseltd

iTrader: (19)

The flutuating idle speed could be caused by a faulty or out of adjustment TPS, dirty TB, IACV, a vacuum leak, poor fuel pressure, head gasket leak or a worn timing chain or sprokets

Trust me, your alternator is just fine. A voltage swing of 1/2 a volt will not cause the idle speed to change. ~13.5V to ~14.5V is an acceptable output from an alternator at idle with no load on it. A battery doesn't cause voltage swings either. A slow idle speed, 625-650 will cause the alternator's output to dip slightly, especially when there is a load on it. Your idle speed should be between 650 - 750. If your idle speed hunts slightly down under 650, you will see your electrical system's voltage/current output drop slightly as well, especially when it's under a load.

I'll see if I can raise your idle speed slightly while I've got the car at my shop.

HarrisH

iTrader: (1)

The TB was cleaned meticiously and the IACV was also cleaned, I doubt I have a vacuum leak I would def. know if I did. Fuel pressure should be fine as the car isn't running rich or lean, head gasket leak should be out of the question since the compression numbers are good and there is no visible smoke or smell from the exhaust, timing chain and sprockets should be good too since the timing on the car seems fine. My idle speed is around 650-675 possibly even 700 don't remember haven't driven the car in a while, when I see you we can check it out. What seizes to amaze me is the fact that every alternator showed different symptoms which automatically lead me to believe it was the alternator. Keep in mind it is NOT a OEM alternator, I presume it's from an auto parts store and it was remanufactured. Regardless, it doesn't cause me any problems but it still does concern me as I am a perfectionist, I also want to check the TPS to make sure it is fine. I hope to see you today Tom I hear they are assembling the car and hopefully they'll be done by 5ish.

HarrisH

iTrader: (1)

And it's also not the idle speed that is fluctuating, I haven't seen it fluctuate in a long long time, it's just the electrical system. So I don't think it might be idle related, I would def. know if it was, the idle from last I remember is pretty smooth just the rapid fluctuation of the charging from the alty., however; on the original alty. the fluctuation would be so harsh that would cause slight fluctuations in idle speed, and adjusting the idle speed did not fix the problem.